1. Field of the Invention
The present invention relates to an information recording card, and an information recording method and an information recognition method each using the card, more particularly to an information recording card comprising a reversible thermosensitive recording portion capable of recording information therein and deleting recorded information therefrom reversibly, and an irreversible recording portion capable of recording information therein, and an information recording method and an information recognition method using such a card.
2. Discussion of Background
Varieties of cards such as prepaid cards and credit cards are currently widely used. Some cards now in general use include a display portion which is capable of displaying, for instance, the balance in the current account, by thermosensitive recording.
Cards of such a thermosensitive recording type, however, use a thermosensitive recording material of the type which does not allow repeated rewriting in the display portion, and the number of the repetition of recording information by rewriting it in the display portion is limited. Furthermore, the size of characters that can be recorded is generally small and the reading thereof is not always easy. In this sense, the cards of the above-mentioned type are not suitable for fine characters such as Chinese characters.
Under such circumstances, it has been proposed to construct a recording display portion of a reversible thermosensitive recording material which is capable of recording information and erasing recorded information reversibly by heating and cooling the reversible thermosensitive recording material, and vice versa.
The thus constructed recording display portion has the advantages that relatively large size characters, not only for the balance in the current account, but also for other detailed information, can be repeatedly written, so that the application of such a reversible thermosensitive recording material to a display portion for information cards attracts attention and is in fact disclosed in Japanese Utility Model Application 2-3876.
However, an information recording card using the above-mentioned thermosensitive recording material in the display portion thereof has the risk that recorded information is altered and falsified, for instance, by altering the balance of a prepaid card to a larger balance than the actual balance in the display portion, or by deleting a "used" notation to make a used card appear a new card, by improperly using the advantage of the information recording card which uses the thermosensitive recording material that recorded information can be rewritten.
Such an altered card cannot be recognized by an information reading apparatus for reading information recorded in the card, and it is conceivable that such altered cards are improperly sold to innocent users. Therefore means for preventing such improper alternation is indispensable.
Japanese Utility Model Application 4-126877 discloses a proposal for preventing such improper alternation in which when a reversible thermosensitive recording portion is heated in an attempt to make an improper alternation, an irreversible thermosensitive sensing portion is colored so that the improper alternation is recognized by the coloring of the irreversible thermosensitive recording portion. In this case, however, it is easy to alter the reversible thermosensitive recording portion by heating only the recording portion without heating the irreversible thermosensitive recording portion.
Furthermore, the temperature at which the color of the irreversible thermosensitive recording portion is changed has to be set at a relatively low temperature. Therefore a card including such a reversible thermosensitive recording portion and an irreversible thermosensitive recording portion happens to be heated to high temperatures, without any intention of making improper alternation, for instance, by the card being placed in a car in the summer, the card will become unusable.